نتایج جستجو برای: planktonic foraminifera

تعداد نتایج: 9925  

Journal: :Marine Micropaleontology 2021

Planktonic foraminifera are important calcifiers in the modern ocean. Despite this importance, main functions of foraminifera's test and ornamentation such as spines unclear. Spinose species dominate planktonic population subtropical oligotrophic gyres, while non-spinose deeper waters at high latitudes suggesting that help food-limited areas. Here we take a novel approach to investigate benefit...

Journal: :Science 2000
M A Maslin S J Burns

Quantifying the moisture history of the Amazon Basin is essential for understanding the cause of rain forest diversity and its potential as a methane source. We reconstructed the Amazon River outflow history for the past 14,000 years to provide a moisture budget for the river drainage basin. The oxygen isotopic composition of planktonic foraminifera recovered from a marine sediment core in a re...

2016
Thomas H. G. Ezard Andy Purvis

Co-dependent geological and climatic changes obscure how species interact in deep time. The interplay between these environmental factors makes it hard to discern whether ecological competition exerts an upper limit on species richness. Here, using the exceptional fossil record of Cenozoic Era macroperforate planktonic foraminifera, we assess the evidence for alternative modes of macroevolution...

Journal: :Science 2011
Thomas H G Ezard Tracy Aze Paul N Pearson Andy Purvis

Ecological change provokes speciation and extinction, but our knowledge of the interplay among the biotic and abiotic drivers of macroevolution remains limited. Using the unparalleled fossil record of Cenozoic macroperforate planktonic foraminifera, we demonstrate that macroevolutionary dynamics depend on the interaction between species' ecology and the changing climate. This interplay drives d...

Journal: :Science 2004
Amelia E Shevenell James P Kennett David W Lea

Magnesium/calcium data from Southern Ocean planktonic foraminifera demonstrate that high-latitude (approximately 55 degrees S) southwest Pacific sea surface temperatures (SSTs) cooled 6 degrees to 7 degrees C during the middle Miocene climate transition (14.2 to 13.8 million years ago). Stepwise surface cooling is paced by eccentricity forcing and precedes Antarctic cryosphere expansion by appr...

2013
Peter J. Leech Rong Zhang

Paleoclimate proxy evidence suggests a southward shift of the Intertropical Convergence Zone (ITCZ) during times of Northern Hemisphere cooling, including the Last Glacial Maximum, 19–23 ka before present. However, evidence for movement over the Pacific has mainly been limited to precipitation reconstructions near the continents, and the position of the Pacific marine ITCZ is less well constrai...

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